JP6393293B2 - Imaging device and imaging apparatus - Google Patents

Description

  The present invention relates to an imaging element and an imaging apparatus.

  In order to detect the focus state of a photographic lens, a solid-state imaging device that performs focus detection of a pupil division method using a CMOS image sensor (solid-state imaging device) used in a digital still camera is disclosed (Patent Document 1). ). The solid-state imaging device of Patent Document 1 has a configuration in which a photoelectric conversion unit is divided into two parts in order to detect the focus state of the photographic lens among some of the pixels constituting the solid-state imaging device. Yes. And the photoelectric conversion part divided | segmented into 2 is comprised so that the predetermined area | region from which the pupil of a photographic lens differs through a microlens, respectively, may be light-received.

  On the other hand, in patent document 2, when the condensing power of the micro lens of the focus detection pixel is insufficient, it is proposed to form an in-layer lens between the micro lens and the photoelectric conversion unit in order to compensate for the insufficient condensing power. Has been.

JP 2005-106994 A JP 2007-281296 A

  By the way, the condensing spot diameter of the microlens cannot be made smaller than the diffraction limit determined by the numerical aperture and the wavelength λ of incident light. That is, light cannot be imaged in a region smaller than the diffraction limit. Therefore, when the pixel size becomes finer as the resolution of the image sensor increases and approaches the diffraction limit, the pupil division performance deteriorates rapidly. Furthermore, when the pixel size is equal to or smaller than the diffraction limit, pupil division using a microlens becomes impossible.

  Therefore, it is necessary to reduce the diffraction limit in order to cope with the miniaturization of the pixel size of the image sensor. However, in the configuration proposed in Patent Document 2, there is a problem that the diffraction limit cannot be made sufficiently small, and the pupil division performance of the focus detection pixel is lowered as the pixel size is miniaturized. Furthermore, in addition to miniaturization of the pixel size for high resolution, if the distance between the microlens and the photoelectric conversion unit is shortened in order to improve the light receiving efficiency of the standard pixel with a back-illuminated image sensor, etc., for focus detection There exists a subject that the pupil division | segmentation performance of a pixel will fall more.

  The present invention has been made in view of the above problems, and an object of the present invention is to satisfactorily maintain the pupil division performance of a pixel that acquires a focus detection signal when the pixel of an image sensor is miniaturized.

In order to achieve the above object, the imaging device of the present invention has a plurality of pixels, and at least some of the plurality of pixels are used for microlens and pupil division type defocus detection, respectively. Output at least one photoelectric conversion unit, an in-layer lens formed between the photoelectric conversion unit and the microlens, and disposed between the in-layer lens and the photoelectric conversion unit A light-shielding layer that has an opening decentered from the optical axis of the microlens and shields at least a part of a light-receiving surface of the photoelectric conversion unit, the inner-layer lens, the light-shielding layer, and the photoelectric of the opening part. and high refractive index layers filling between the light receiving surface of the converter unit, a between the micro lens and the light-shielding layer is configured to fill the periphery of the high refractive index layer, the high Less than the refractive index of the refractive index layer And a low refractive index layer having a Oriritsu, the high refractive index layer has a refractive index for condensing incident light on the light receiving surface by the layer lens and the microlens.

  ADVANTAGE OF THE INVENTION According to this invention, when the pixel of an image pick-up element is refined | miniaturized, the pupil division | segmentation performance of the pixel which acquires the signal for focus detection can be maintained favorable.

1 is a diagram showing a schematic configuration of a camera according to an embodiment of the present invention. 1 is a diagram illustrating a schematic circuit configuration of an image sensor according to an embodiment. FIG. 4 is a schematic plan view of imaging pixels according to the embodiment and a diagram for explaining a relationship between imaging pixels and an exit pupil. FIG. 3 is a schematic plan view of focus detection pixels according to the first embodiment and a diagram for explaining a relationship between the focus detection pixels and the exit pupil. FIG. 3 is a schematic cross-sectional view of a focus detection pixel in which an opening of a cross-sectional light shielding layer of the focus detection pixel in the first embodiment is filled with a high refractive index layer. FIG. 6 is a schematic cross-sectional view for explaining a diffraction limit of a conventional focus detection pixel in which an opening of a light shielding layer is filled with a low refractive index layer. FIG. 3 is a schematic cross-sectional view for explaining a diffraction limit of the focus detection pixel of the first embodiment in which an opening of a light shielding layer is filled with a high refractive index layer. FIG. 6 is a schematic cross-sectional view of a focus detection pixel according to a second embodiment in which a light receiving surface of a divided photoelectric conversion unit is filled with a high refractive index layer. FIG. 6 is a schematic cross-sectional view of a focus detection pixel according to a third embodiment in which an opening of a light shielding layer formed on a light receiving surface of an optical waveguide is filled with a high refractive index layer. An example of numerical analysis of a focus detection pixel in which an opening of a light shielding layer formed on a light receiving surface of an optical waveguide is filled with a high refractive index layer. The pupil intensity distribution example of the pixel for a focus detection by which the opening part of the light shielding layer formed in the light-receiving surface of an optical waveguide is filled with the high refractive index layer.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components exemplified in this embodiment should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. However, the present invention is not limited to these examples.

<First Embodiment>
FIG. 1 shows a schematic configuration of a camera which is an image pickup apparatus having a focus detection apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a first lens group disposed at the tip of a photographing optical system (imaging optical system), which is held so as to be able to advance and retract in the optical axis direction. Reference numeral 102 denotes an aperture / shutter, which adjusts the light amount at the time of shooting by adjusting the aperture diameter, and also has a function as an exposure time adjustment shutter at the time of still image shooting. Reference numeral 103 denotes a second lens group. The diaphragm / shutter 102 and the second lens group 103 integrally move forward and backward in the optical axis direction, and a zooming function can be realized by interlocking with the forward and backward movement of the first lens group 101.

  Reference numeral 105 denotes a third lens group that performs focus adjustment by advancing and retreating in the optical axis direction. Reference numeral 106 denotes an optical low-pass filter, which is an optical element for reducing false colors and moire in a captured image. Reference numeral 107 denotes an image sensor composed of a CMOS sensor and its peripheral circuits. As the image sensor 107, a two-dimensional single-plate color sensor in which a Bayer array primary color mosaic filter is formed on-chip on light receiving pixels of horizontal m pixels and vertical n pixels is used.

  A zoom actuator 111 rotates a cam cylinder (not shown) to drive the first lens group 101 to the third lens group 103 back and forth in the optical axis direction and perform a zooming operation. Reference numeral 112 denotes an aperture shutter actuator that controls the aperture diameter of the aperture / shutter 102 to adjust the amount of photographing light, and controls the exposure time during still image photographing. Reference numeral 114 denotes a focus actuator that performs focus adjustment by driving the third lens group 105 back and forth in the optical axis direction.

  Reference numeral 115 denotes an electronic flash for illuminating a subject at the time of photographing, and a flash illumination device using a xenon tube is suitable, but an illumination device including an LED that emits light continuously may be used. Reference numeral 116 denotes an AF auxiliary light emitting unit that projects an image of a mask having a predetermined aperture pattern onto a subject field via a light projection lens, and improves focus detection capability for a dark subject or a low-contrast subject.

  Reference numeral 121 denotes an in-camera CPU that controls various controls of the camera body, and includes a calculation unit, ROM, RAM, A / D converter, D / A converter, communication interface circuit, and the like. The CPU 121 drives various circuits included in the camera based on a predetermined program stored in the ROM, and executes a series of operations such as AF, photographing, image processing, and recording.

  An electronic flash control circuit 122 controls lighting of the electronic flash 115 in synchronization with the photographing operation. Reference numeral 123 denotes an auxiliary light driving circuit that controls the lighting of the AF auxiliary light emitting unit 116 in synchronization with the focus detection operation. An image sensor driving circuit 124 controls the image capturing operation of the image sensor 107 and A / D converts the acquired image signal and transmits the image signal to the CPU 121. An image processing circuit 125 performs processing such as γ conversion, color interpolation, and JPEG compression of an image acquired by the image sensor 107.

  A focus drive circuit 126 controls the focus actuator 114 based on the focus detection result, and adjusts the focus by driving the third lens group 105 back and forth in the optical axis direction. Reference numeral 128 denotes an aperture shutter drive circuit which controls the aperture shutter actuator 112 to control the aperture of the aperture / shutter 102. Reference numeral 129 denotes a zoom drive circuit that drives the zoom actuator 111 in accordance with the zoom operation of the photographer.

  Reference numeral 131 denotes a display device such as an LCD, which displays information related to the shooting mode of the camera, a preview image before shooting and a confirmation image after shooting, a focus state display image at the time of focus detection, and the like. An operation switch group 132 includes a power switch, a release (shooting trigger) switch, a zoom operation switch, a shooting mode selection switch, and the like. Reference numeral 133 denotes a detachable flash memory that records a photographed image.

  FIG. 2 shows a schematic circuit configuration of the image sensor according to the first embodiment of the present invention. FIG. 2 shows a range of 2 columns × 4 rows of pixels in a two-dimensional CMOS area sensor composed of a large number of pixels. When the image sensor 107 is used, the pixels shown in FIG. A large number are arranged to enable acquisition of high-resolution images. In the first embodiment, light is incident on the photodiode from a surface opposite to the surface on which the circuit is formed. That is, a circuit is formed below the photodiode in the light incident direction. The backside-illuminated imaging device will be described.

In FIG. 2, 1 is a photoelectric conversion portion of a photoelectric conversion element comprising a MOS transistor gate and a depletion layer under the gate, 2 is a photogate, 3 is a transfer switch MOS transistor, 4 is a reset MOS transistor, and 5 is a source follower amplifier MOS. It is a transistor. Reference numeral 6 denotes a horizontal selection switch MOS transistor, and reference numeral 7 denotes a load MOS transistor of a source follower. 8 is a dark output transfer MOS transistor, 9 is a light output transfer MOS transistor, 10 is a dark output storage capacitor C _TN , 11 is a light output storage capacitor C _TS , and 12 is a horizontal transfer MOS transistor. 13 is a horizontal output line reset MOS transistor, 14 is a differential output amplifier, 15 is a horizontal scanning circuit, and 16 is a vertical scanning circuit.

  3 and 4 are diagrams illustrating the structures of the imaging pixel and the focus detection pixel, respectively. In the first embodiment, out of 4 pixels of 2 rows × 2 columns, pixels having G (green) spectral sensitivity are arranged in the diagonal 2 pixels, and R (red) and B are arranged in the other 2 pixels. A Bayer arrangement in which one pixel each having (blue) spectral sensitivity is arranged is employed. Then, a plurality of focus detection pixels having the structure described later shown in FIG. 4 are distributed and arranged in a predetermined rule between the Bayer arrays.

  FIG. 3A is a plan view of 2 × 2 imaging pixels located near the center of the image sensor 107. In the Bayer array, G pixels are arranged diagonally, R and B pixels are arranged in the other two pixels, and a structure of 2 rows × 2 columns is repeatedly arranged. FIG. 3B is a view showing a cross section AA of FIG. ML is an on-chip microlens disposed on the forefront of each pixel, CFR is an R (red) color filter, and CFG is a G (green) color filter. PD schematically shows the photoelectric conversion unit 1 of the CMOS sensor described in FIG. 2, and CL is a wiring layer for forming signal lines for transmitting various signals in the CMOS sensor. TL schematically shows the photographing optical system.

  Here, the microlens ML and the photoelectric conversion unit PD of the imaging pixel are configured to capture the light beam that has passed through the photographing optical system TL as effectively as possible. The exit pupil EP of the photographic optical system TL and the photoelectric conversion unit PD are in a conjugate relationship by the microlens ML, and the effective area of the photoelectric conversion unit PD is designed to be large. 3B, the incident light flux of the R pixel has been described, but the G pixel and the B (blue) pixel have the same structure. Accordingly, the exit pupil EP corresponding to each of the RGB pixels for imaging has a large diameter, and the S / N of the image signal is improved by efficiently capturing the light flux from the subject.

FIG. 4A is a plan view of pixels of 2 rows × 2 columns including focus detection pixels for pupil division in the x direction in the drawing of the photographing lens located near the center of the image sensor 107. When obtaining an imaging signal, the G pixel is a main component of luminance information. Since human image recognition characteristics are sensitive to luminance information, image quality degradation is likely to be noticed when G pixels are missing. On the other hand, the R or B pixel is a pixel that acquires color information. However, since humans are insensitive to color information, pixels that acquire color information are less likely to notice image quality deterioration even if there are some defects. Therefore, in the first embodiment, among the pixels of 2 rows × 2 columns, the G pixel is left as an imaging pixel, and the focus detection pixel is in a certain ratio to a part of the pixels at positions corresponding to R and B. Is arranged. This is indicated by S _HA and S _HB in FIG.

FIG. 4B is a view showing a cross section BB of FIG. The microlens ML and the photoelectric conversion unit PD have the same structure as the imaging pixel shown in FIG. In the first embodiment, since the signal of the focus detection pixel is not used for generating a captured image, a transparent film CF _W (colorless) is disposed instead of the color filter for color separation. Further, since pupil division is performed by the image sensor 107, the opening of the wiring layer CL is decentered in the x direction with respect to the center line of the microlens ML. Specifically, since the opening OP _HA of the pixel S _HA is decentered in the −x direction, the light beam that has passed through the left exit pupil EP _HA of the imaging optical system TL is received. Similarly, since the opening OP _HB of the pixel S _HB is decentered in the + x direction, the light beam that has passed through the right exit pupil EP _HB of the photographing optical system TL is received. Here, the pixels _SHA are regularly arranged in the x direction, and the subject image acquired by these pixel groups is defined as an A image. Similarly, the pixels _SHB are also regularly arranged in the x direction, and a subject image acquired by these pixel groups is defined as a B image. By detecting the relative positions of these A and B images, the amount of defocus (defocus amount) of the subject image can be detected.

Note that, in the pixels S _HA and S _HB , focus detection is possible for an object having a luminance distribution in the x direction on the photographing screen, for example, a line in the y direction. If necessary, a pixel that performs pupil division in the y direction of the photographic lens may be provided so that focus detection can be performed on a subject having a luminance distribution in the y direction of the photographic screen, for example, a line in the x direction. .

Structure of Focus Detection Pixel Next, FIG. 5A shows the structure of the focus detection pixel for the A image in the first embodiment, and FIG. 5B shows the structure of the focus detection pixel for the B image. ). PD-A and PD-B are photoelectric conversion units, and ML is a microlens. A low refractive index layer LL having a refractive index equal to or lower than the refractive index of the microlens ML is formed between the photoelectric conversion units PD-A and PD-B and the microlens ML. A color filter (CF) layer may be disposed as necessary. The microlens ML and the low refractive index layer LL are made of a polymer, silica SiO ₂ or the like, and the refractive index in the visible range is about 1.4 to 1.8. Between the photoelectric conversion units PD-A and PD-B and the microlens ML, light shielding layers SL-A and SL-B having openings formed for pupil division are arranged. The openings of the light shielding layers SL-A and SL-B are configured to be eccentric from the optical axis of the microlens ML in opposite directions. The light shielding layer is made of a multilayer interference film such as titanium Ti or aluminum Al and titanium nitride TiN, or a material having a large absorption coefficient in the visible region.

Further, in the first embodiment, an intralayer lens having a refractive index larger than the refractive index of the low refractive index layer LL between the light shielding layers SL-A and SL-B having openings and the microlens ML. ML2 is formed. Furthermore, from the inner lens ML2 to the openings of the light shielding layers SL-A and SL-B, the microlens ML side of the openings of the light shielding layers SL-A and SL-B is at least larger than the refractive index of the low refractive index layer LL. It is filled with a high refractive index layer HL having a refractive index. Furthermore, an optical system including the microlens ML and the in-layer lens ML2 is configured to focus incident light near the light receiving surfaces of the photoelectric conversion units PD-A and PD-B. The intralayer lens ML2 and the high refractive index layer HL are made of silicon nitride SiN _x , silicon nitride oxide SiN _x O _y , titanium oxide TiO ₂ , niobium oxide, ITO, IZO, or the like. The refractive index in the visible range is about 1.8 to 2.5, which is higher than the refractive index of the low refractive index layer LL.

  Such a configuration makes it possible to reduce the diffraction limit of the focused spot, reduce the pixel size of the image sensor, and reduce the distance between the microlens and the photoelectric conversion unit. Good pupil division performance can be maintained.

  The effects of the present invention will be described below. FIG. 6 shows a pixel in which the space between the openings of the inner lens ML2 and the light shielding layer SL is filled with the low refractive index layer LL in the conventional example. On the other hand, FIG. 7 shows a pixel according to the first embodiment of the present invention in which the space between the opening of the inner lens ML2 and the light shielding layer SL is filled with the high refractive index layer HL. 6 and 7, (a) shows the state in which the incident lights L1 and L2 are incident on the focus detection pixels at an angle parallel to the optical axis of the microlens, and (b) shows the optical axis of the microlens. 2 shows a state in which incident light L1 and L2 are incident on the focus detection pixels at an oblique angle.

  6 and 7, PD is a photoelectric conversion unit, ML is a microlens, ML2 is an in-layer lens, LL is a low refractive index layer, HL is a high refractive index layer, and SL is a light shielding layer having an opening. P is the pixel period (pixel width), D is the interlayer film thickness (distance from the microlens ML to the photoelectric conversion part PD or the light shielding layer SL), and W is the slit width (width of the opening of the light shielding layer). Δ is the diffraction limit of the imaging system formed by the microlens ML and the in-layer lens ML2. In this example, the wavelength of incident light is 540 nm, the refractive index of the microlens ML is 1.6, the refractive index of the low refractive index layer LL is 1.45, and the refractive indexes of the inner lens ML2 and the high refractive index layer HL are 2. Three.

  Incident light is condensed at the imaging position by the microlens ML and the in-layer lens ML2. However, due to the wave nature of light, the diameter of the focused spot cannot be made smaller than the diffraction limit Δ. The diffraction limit Δ is approximately expressed by Equation (1), where λ is the wavelength of incident light, n is the refractive index of the imaging position, and θ is half the expected angle of the optical system that combines the microlens and the in-layer lens. Can be estimated.

In a normal imaging device, since the wiring layer is disposed between the light receiving surface of the photoelectric conversion unit and the microlens, the interlayer film thickness D is longer than the pixel period P. When the pixel period P is 2.0 μm and the interlayer film thickness D is 4.0 μm, the angle θ which is half of the expected angle is about 14 °. When the wavelength λ of incident light is 0.54 nm and the refractive index of the transparent layer TR made of silica SiO ₂ is 1.46, the diffraction limit Δ is about 1.9 μm. Therefore, the diffraction limit, which is the limit of the focused spot diameter, is approximately the same as the pixel period, and pupil division is impossible.

  In order to make the diffraction limit smaller, it is necessary to shorten the interlayer film thickness D with respect to the pixel period P and increase the prospective angle 2θ. In the case of a back-illuminated image sensor, the interlayer film thickness D can be shortened with respect to the pixel period P.

  However, in the conventional pixel shown in FIG. 6, since the space between the opening of the light shielding layer SL and the inner lens ML2 is filled with the low refractive index layer LL, the interlayer film thickness D is shorter than the pixel period P. However, the diffraction limit Δ has the following limitations. That is, even if the condensing power of the microlens ML and the inner lens ML2 is increased to increase the expected angle 2θ, total reflection occurs between the bottom surface of the inner lens ML2 and the low refractive index layer LL. The angle 2θ cannot be increased beyond a certain value. Further, the incident light L1 indicated by the solid line reaches the opening of the light shielding layer SL, but the incident light L2 indicated by the broken line cannot reach the opening of the light shielding layer SL, so that the substantial aperture ratio of the microlens ML is increased. The light receiving efficiency is also reduced. In particular, as shown in FIG. 6B, when the light is incident obliquely with respect to the optical axis of the microlens, the light receiving efficiency is greatly reduced.

  On the other hand, in the present invention shown in FIG. 7, since the space between the opening of the light shielding layer SL and the inner lens ML2 is filled with the high refractive index layer HL, total reflection as described in FIG. 6 occurs. And the diffraction limit Δ can be reduced. As can be seen from Equation (1), since the refractive index n is increased, the diffraction limit Δ can be made smaller than that of the conventional example. Further, the substantial aperture ratio of the microlens ML does not decrease. When the pixel period P is 2.0 μm, the interlayer film thickness D is 1.0 μm, and the refractive index of the high refractive index layer is 2.3, the diffraction limit Δ is about 370 nm, and pupil division can be performed even with a smaller pixel period. it can.

  Therefore, with the configuration described above, even when the pixel size of the image sensor is miniaturized and the distance between the microlens and the photoelectric conversion unit is shortened, the pupil division performance of the focus detection pixel can be maintained well. .

  In the present embodiment, the description has been made on the image pickup element that performs pupil division by the light shielding layer having the opening. However, as illustrated in FIG. 8, the light receiving surface of the divided photoelectric conversion unit is formed by the high refractive index layer. A filled image sensor may be used.

<Second Embodiment>
The structure of the focus detection pixel in the second embodiment of the present invention is shown in FIG. PD-A and PD-B are photoelectric conversion units, and ML is a microlens. A low refractive index layer LL having a refractive index equal to or lower than the refractive index of the microlens ML is formed between the photoelectric conversion units PD-A and PD-B and the microlens ML. A color filter (CF) layer may be disposed as necessary. For one pupil lens ML, the photoelectric conversion unit is divided into a plurality (two or more) of PD-A and PD-B for pupil division. The photoelectric conversion units PD-A and PD -B is decentered in the opposite direction from the optical axis of the microlens.

  In the second embodiment, the inner lens having a refractive index larger than the refractive index of the low refractive index layer LL between the divided light receiving surfaces of the photoelectric conversion units PD-A and PD-B and the microlens ML. ML2 is formed. Further, the microlens ML side of the light receiving surfaces of the photoelectric conversion units PD-A and PD-B extends from the inner lens ML2 to the light receiving surfaces of the photoelectric conversion units PD-A and PD-B divided by the low refractive index layer LL. It is filled with a high refractive index layer HL having a refractive index greater than the refractive index. Furthermore, the optical system that combines the microlens ML and the in-layer lens ML2 is configured to focus incident light near the light receiving surfaces of the photoelectric conversion units PD-A and PD-B.

  Assuming that the subject image acquired by the photoelectric conversion unit PD-A is an A image and the subject image acquired by the photoelectric conversion unit PD-B is a B image, by detecting the relative position of the A image and the B image, The amount of focus deviation (defocus amount) can be detected. Further, the subject image acquired by the photoelectric conversion unit PD-A and the subject image acquired by the photoelectric conversion unit PD-B are added to obtain a captured image.

  Therefore, with the configuration described above, even when the pixel size of the image sensor is miniaturized and the distance between the microlens and the photoelectric conversion unit is shortened, the pupil division performance of the focus detection pixel can be maintained well. .

<Third Embodiment>
FIG. 9A shows the structure of the focus detection pixel for the A image according to the third embodiment of the present invention, and FIG. 9B shows the structure of the focus detection pixel for the B image. PD-A and PD-B are photoelectric conversion units, and ML is a microlens. A low refractive index layer LL having a refractive index equal to or lower than the refractive index of the microlens ML is formed between the photoelectric conversion units PD-A and PD-B and the microlens ML. In the low refractive index layer LL, an optical waveguide LG having a refractive index larger than that of the low refractive index layer LL is formed. A color filter (CF) layer may be disposed as necessary. Light shielding layers SL-A and SL-B having openings for pupil division are arranged between the optical waveguide LG and the microlens ML. The openings of the light shielding layers SL-A and SL-B are configured to be eccentric from the optical axis of the microlens ML in opposite directions. Here, in the imaging pixel (not shown), the opening of the light shielding layer is formed wider than the focus detection pixel.

  In the third embodiment, the inner lens ML2 having a refractive index larger than the refractive index of the low refractive index layer LL is formed between the light shielding layers SL-A and SL-B having the openings and the microlens ML. Is done. Furthermore, from the inner lens ML2 to the openings of the light shielding layers SL-A and SL-B, the microlens ML side of the openings of the light shielding layers SL-A and SL-B is at least larger than the refractive index of the low refractive index layer LL. The high refractive index layer HL is filled. Furthermore, an optical system that combines the microlens ML and the in-layer lens ML2 is configured to focus incident light near the light receiving surface of the optical waveguide LG.

The microlens ML and the low refractive index layer LL are made of a polymer, silica SiO ₂ or the like, and the refractive index in the visible range is about 1.4 to 1.8. The optical waveguide LG, the intralayer lens ML2, and the high refractive index layer HL are made of silicon nitride SiN _x , silicon nitride oxide SiN _x O _y , titanium oxide TiO ₂ , niobium oxide, ITO, IZO, or the like. The refractive index in the visible range is about 1.8 to 2.5, which is higher than the refractive index of the low refractive index layer LL.

  FIG. 10 shows a numerical calculation example based on electromagnetic wave analysis when light is incident on the focus detection pixel (pixel period: 1.65 μm) for the A image in the third embodiment from above the microlens ML. The stronger the light intensity, the brighter it is shown. FIG. 10A shows a case where light is incident on the focus detection pixel at −10 °, and most of the light is blocked by the light blocking layer. On the other hand, FIG. 10B shows a case where light is incident on the focus detection pixel at 0 °, and FIG. 10C is 10 ° on the focus detection pixel. Light reaches the photoelectric conversion unit.

  FIG. 11 shows an example of the pupil intensity distribution of the imaging pixels in the third embodiment by a solid line and an example of the pupil intensity distribution of the focus detection pixels for the A image by a broken line. The horizontal axis represents the incident angle of light incident on the pixel, and the vertical axis represents the received light intensity. It can be seen that a favorable pupil division characteristic can be obtained by the configuration of the third embodiment.

  Therefore, with such a configuration, it becomes possible to reduce the diffraction limit of the focused spot, and even if the pixel size of the image sensor is miniaturized, the pupil division performance of the focus detection pixels can be maintained well. .

1: Photoelectric conversion unit, 107: Image sensor, ML: Micro lens, ML2: In-layer lens, PD-A, PD-B: Photoelectric conversion unit, HL: High refractive index layer, LL low refractive index layer, SL-A , SL-B: light shielding layer, CL: wiring layer, CFR, CFG: color filter, CF _W : transparent film

Claims (7)

A plurality of pixels, and at least some of the plurality of pixels are respectively
A microlens,
At least one photoelectric conversion unit that outputs a signal used for pupil-division defocus detection;
An in-layer lens formed between the photoelectric conversion unit and the microlens;
A light-shielding layer that is disposed between the intra-layer lens and the photoelectric conversion unit, has an opening decentered from the optical axis of the microlens, and shields at least part of the light-receiving surface of the photoelectric conversion unit;
Said layer lens, a high refractive index layer which is Filling between the shielding layer and the light-receiving surface of the photoelectric conversion portion of the opening portion,
A between the light-shielding layer and the microlens being arranged to fill the periphery of the high refractive index layer, it has a low refractive index layer having a refractive index less than a refractive index of the high refractive index layer And
The imaging device, wherein the high refractive index layer has a refractive index for condensing incident light on the light receiving surface by the microlens and the in-layer lens .   The imaging device according to claim 1, wherein a distance between a bottom surface of the microlens and a light receiving surface of the photoelectric conversion unit is shorter than a period of the pixels.   The imaging device according to claim 1, further comprising a wiring layer on a side opposite to the microlens of the photoelectric conversion unit. The said some pixel which has the said photoelectric conversion part which outputs the signal used for a focus detection is distributedly arrange | positioned among these pixels, The one of Claim 1 thru | or 3 characterized by the above-mentioned. Image sensor. The plurality of pixels include a Bayer color filter.
The said some pixel which has the said photoelectric conversion part which outputs the signal used for a focus detection replaces with the said color filter, The transparent film is provided in any one of Claim 1 thru | or 4 characterized by the above-mentioned. Image sensor. A plurality of pixels, and at least some of the plurality of pixels are respectively
A microlens,
At least one photoelectric conversion unit that outputs a signal used for pupil-division defocus detection;
An in-layer lens formed between the photoelectric conversion unit and the microlens and having a bottom surface on the photoelectric conversion unit side;
A light-shielding layer that is disposed between the intra-layer lens and the photoelectric conversion unit, has an opening decentered from the optical axis of the microlens, and shields at least part of the light-receiving surface of the photoelectric conversion unit;
Said layer lens, and the light shielding layer and the filled between the photoelectric conversion portion of the light receiving surface, reflection reducing layer for reducing the total reflection by the bottom surface of the layer lens of the opening portion,
A low refractive index layer between the microlens and the light shielding layer and configured to fill the periphery of the reflection reducing layer, and having a refractive index equal to or lower than the refractive index of the reflection reducing layer ;
The imaging element, wherein the reflection reducing layer is formed in contact with a bottom surface of the in-layer lens. Imaging apparatus characterized by including an imaging device according to any one of claims 1 to 6.